A FEW WEEKS ago, while I was on vacation, my cell phone rang; it was Jorge Bolaños, head of the Cuban mission in Washington. “I have a message for you from Fidel,” he said. This made me sit up straight. Castro had read my recent Atlantic Monthly cover story about Israel and Iran, Bolaños told me. “He invites you to Havana on Sunday to discuss the article.” I am, of course, always eager to interact with readers of The Atlantic, so I called a friend at the Council on Foreign Relations, Julia Sweig, who is a pre-eminent expert on Cuba and Latin America: “Road trip,” I said.

I quickly departed the People’s Republic of Martha’s Vineyard for Fidel’s more tropical socialist island paradise. Despite the American ban on travel to Cuba, both Julia and I, as journalists and researchers, qualified for a State Department exemption. Our charter flight from Miami, which was bursting with Cuban-Americans carrying flat-screen televisions and computers for their technologically bereft families, took just 50 minutes to reach a mostly empty José Martí International Airport. Soon, Julia and I were deposited at a “protocol house” in a mostly empty government compound whose architecture reminded me of the gated communities of Boca Raton, Fla.

I was aware that Castro had become preoccupied with the threat of a military confrontation in the Middle East between Iran and the U.S. (and Israel, the country he calls its Middle East “gendarme”). Since emerging from his medically induced, four-year purdah early this summer (various gastrointestinal maladies had combined to nearly kill him), the 84-year-old Castro has spoken mainly about the catastrophic threat of what he sees as an inevitable war. Still, I was curious to know why he saw conflict as unavoidable, and I wondered, of course, if personal experience—the Cuban missile crisis of 1962—informed his belief that a conflict between America and Iran would escalate into nuclear war. I was even more curious, however, to get a glimpse of the great man. Few people had seen him since he fell ill in 2006, and the state of his health has been a subject of much speculation. There were questions, too, about the role he plays now in governing Cuba; he formally handed off power to his younger brother, Raúl, two years ago, but it was not clear how many strings Fidel still pulled.

There were many odd things about my recent Havana stopover, but one of the most unusual was Fidel Castro’s level of self-reflection. Perhaps most striking was something he said at lunch on the day of our first meeting. We were seated around a smallish table: Castro; his wife, Dalia; his son Antonio; Randy Alonso, a major figure in the government-run media; my friend Julia, and I. I initially was mainly interested in watching Fidel eat (for the record, he ingested small amounts of fish and salad, and quite a bit of bread dipped in olive oil, as well as a glass of red wine). But during the meal’s generally lighthearted conversation, I asked him if he believed the Cuban model was still something worth exporting.

“The Cuban model doesn’t even work for us anymore,” he said.

Wait: Did the leader of the Revolution just say, in essence, “Never mind”?

Later, I asked Julia to interpret this stunning statement for me. She said, “He wasn’t rejecting the ideas of the Revolution. I took it to be an acknowledgment that under ‘the Cuban model’ the state has much too big a role in the economic life of the country.”

Julia pointed out that one effect of such a sentiment might be to create space for Raúl, who is now president, to enact the necessary reforms in the face of what will surely be push-back from orthodox communists within the party and the bureaucracy. Raúl Castro is already loosening the state’s hold on the economy. He recently announced, in fact, that small businesses can now operate and that foreign investors can now buy Cuban real estate. (The joke of this new announcement, of course, is that Americans are not allowed to invest in Cuba, not because of Cuban policy, but because of American policy.)

But I digress. Toward the end of this long, relaxed lunch, Fidel proved to us that he was truly semi-retired. The next day was Monday, when maximum leaders are expected to be busy single-handedly managing their economies, throwing dissidents into prison, and the like. But Fidel’s calendar was open. He asked us, “Would you like to go to the aquarium with me to see the dolphin show?”

Again, I wasn’t sure I’d heard him correctly. “The dolphin show?” “The dolphins are very intelligent animals,” Castro said. I noted that we had a meeting scheduled for the next morning, with Adela Dworin, the president of Cuba’s Jewish community. “Bring her,” Fidel said.

But I’ll get back to the dolphins. Castro had had other issues on his mind when he extended his invitation.

MY MEETING WITH Fidel had begun some hours earlier. That morning, Julia and I were driven from our compound to a nearby convention center, and escorted to a large, spare office. A frail and aged Fidel stood to greet us. He was wearing a red shirt, sweatpants, and black New Balance sneakers. The room was crowded with officials and family, as well as an Interior Ministry general, a translator, a doctor, and several bodyguards, all of whom appeared to have been recruited from the Cuban national wrestling team. Two of these bodyguards held Castro at the elbow.

We shook hands, and he greeted Julia warmly; they have known each other for more than 20 years. Fidel lowered himself into his seat, and we began a conversation that would continue, in fits and starts, for three days. His body may be frail, but his mind is acute, his energy level is high, and not only that: The late-stage Fidel Castro turns out to possess something of a self-deprecating sense of humor. When I asked him, over lunch, whether his illness caused him to change his mind about the existence of God, he answered, “Sorry, I’m still a dialectical materialist.”

Castro opened our initial meeting by telling me that he’d read my article carefully, and that it confirmed his view that Israel and America were moving precipitously and gratuitously toward confrontation with Iran. This interpretation was not surprising: Castro is the grandfather of global anti-Americanism, and he has been a severe critic of Israel. His message to Benjamin Netanyahu, the Israeli prime minister, he said, was simple: Israel will only have security if it gives up its nuclear arsenal, and the rest of the world’s nuclear powers will only have security if they, too, give up their weapons. Global and simultaneous nuclear disarmament is, of course, a worthy goal, but it is not, in the short term, realistic.

Castro’s message to Mahmoud Ahmadinejad, the president of Iran, was not so abstract, however. Over the course of this first, five-hour discussion, Castro repeatedly returned to the topic of anti-Semitism. He criticized Ahmadinejad for denying the Holocaust and explained why the Iranian government would better serve the cause of peace by acknowledging the “unique” history of anti-Semitism and trying to understand why Israelis fear for their existence. “The Iranians are not going to back down in the face of threats,” he said. “Men think they can control themselves, but Obama could overreact and a gradual escalation could become a nuclear war.” I asked him if this fear was informed by his own experiences during the 1962 missile crisis, when the Soviet Union and the U.S. nearly went to war over the presence of nuclear-tipped missiles in Cuba. I mentioned to Castro the letter he wrote to Nikita Khrushchev, the Soviet premier, at the height of the crisis, in which he recommended that the Soviets consider launching a nuclear strike against the U.S. if the Americans attacked Cuba. “That would be the time to think about liquidating such a danger forever through a legal right of self-defense,” Castro wrote at the time.

I asked him, “At a certain point it seemed logical for you to recommend that the Soviets bomb the U.S. Does what you recommended still seem logical now?” He answered: “After I’ve seen what I’ve seen, and knowing what I know now, it wasn’t worth it all.”

I was surprised to hear Castro express such doubts about his own behavior in the missile crisis—and I was, I admit, also surprised to hear him express such sympathy for Jews, and for Israel’s right to exist (which he endorsed unequivocally).

After this first meeting, I asked Julia to explain the meaning of Castro’s invitation to me, and of his message to Ahmadinejad. “Fidel is at an early stage of reinventing himself as a senior statesman, not as head of state, on the domestic stage, but primarily on the international stage,” she said. “Nuclear proliferation, climate change, these are the major issues for him, and he’s just getting started, using any potential media platform to communicate his views. He has time on his hands now that he didn’t expect to have.”

THE NEXT MORNING, it was time to see the dolphins. We met Fidel on the steps of the dolphin house and went together into a large, blue-lit room that faced a massive, glass-enclosed dolphin tank. Fidel explained, at length, that the Havana Aquarium’s dolphin show was the best dolphin show in the world, “completely unique,” in fact, because it is an underwater show. Three human divers enter the water, without breathing equipment, and perform intricate acrobatics with the dolphins. “Do you like dolphins?” Fidel asked. “I like dolphins a lot,” I said.

Fidel called over Guillermo Garcia, the director of the aquarium, and told him to sit with us. “Goldberg,” Fidel said, “ask him questions about dolphins.” “What kind of questions?” I asked. “You’re a journalist, ask good questions,” he said, and then interrupted himself: “He doesn’t know much about dolphins anyway,” he said, pointing to Garcia. “He’s actually a nuclear physicist.” “Why are you running the aquarium?” I asked Garcia. “We put him here to keep him from building nuclear bombs!” Fidel said, and then cracked up laughing. “In Cuba, we would only use nuclear power for peaceful means,” Garcia said.

A moment later, Fidel pressed me again: “Goldberg, ask your questions about dolphins.” Now on the spot, I turned to Garcia: “How much do the dolphins weigh?” They weigh between 100 and 150 kilograms, he said. “How do you train the dolphins to do what they do?” I asked. “That’s a good question,” Fidel said. Garcia called over one of the aquarium’s veterinarians to help answer the question. Her name was Celia. A few minutes later, Antonio Castro told me her last name: Guevara.

“You’re Che’s daughter?” I asked. “Yes,” she said. “And you’re a dolphin veterinarian?” “I take care of all the inhabitants of the aquarium,” she said. “Che liked animals very much,” Antonio Castro said.

It was time for the show to start. The lights dimmed, and the divers entered the water. Without describing it overly much, I will say that to my surprise, I found myself agreeing with Fidel: The aquarium in Havana puts on a fantastic dolphin show, the best I’ve ever seen, and as the father of three children, I’ve seen a lot of dolphin shows. I will also say this: I’ve never seen someone enjoy a dolphin show as much as Fidel Castro.